Mega is a
unit prefix A unit prefix is a specifier or mnemonic that is prepended to units of measurement to indicate multiples or fractions of the units. Units of various sizes are commonly formed by the use of such prefixes. The prefixes of the metric system, such as ...
in
metric system
The metric system is a system of measurement that succeeded the decimalised system based on the metre that had been introduced in France in the 1790s. The historical development of these systems culminated in the definition of the Interna ...
s of units denoting a factor of one million (10
6 or
). It has the unit symbol M. It was confirmed for use in the
International System of Units (SI) in 1960. ''Mega'' comes from grc, μέγας, mégas, great.
Common examples of usage
*
Megapixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device.
In most digital display devices, pixels are the sm ...
: 1 million
pixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device.
In most digital display devices, pixels are the ...
s in a digital camera
* One megatonne of
TNT equivalent
TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a ...
amounts to approx. 4
petajoules and is the approximate energy released on igniting one million tonnes of TNT. The unit is often used in measuring the explosive power of
nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bom ...
s.
*
Megahertz: frequency of
electromagnetic radiation
In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visible) li ...
for radio and television broadcasting,
GSM
The Global System for Mobile Communications (GSM) is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation ( 2G) digital cellular networks used by mobile devices such ...
, etc. 1 MHz = 1,000,000
Hz.
*
Megabyte: unit of information equal to one million bytes (SI standard).
*
Megawatt
The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James ...
: equal to one million watts of power. It is commonly used to measure the output of
power plant
A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the electricity generation, generation of electric power. Power stations are generally connected to an el ...
s, as well as the power consumption of
electric locomotive
An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a battery or a supercapacitor. Locomotives with on-board fuelled prime movers, such as diesel engines or g ...
s,
data centers, and other entities that heavily consume electricity.
* Megadeath: (or megacorpse) is one million human deaths, usually used in reference to projected number of deaths from a
nuclear explosion
A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, tho ...
. The term was used by scientists and thinkers who strategized likely outcomes of
all-out nuclear warfare.
Exponentiation
When units occur in
exponentiation
Exponentiation is a mathematical operation, written as , involving two numbers, the '' base'' and the ''exponent'' or ''power'' , and pronounced as " (raised) to the (power of) ". When is a positive integer, exponentiation corresponds to r ...
, such as in square and cubic forms, any multiples-prefix is considered part of the unit, and thus included in the exponentiation.
* 1 Mm
2 means one square
megametre or the size of a
square
In Euclidean geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90- degree angles, π/2 radian angles, or right angles). It can also be defined as a rectangle with two equal-length a ...
of by or , and not (10
6 m
2).
* 1 Mm
3 means one cubic
megametre or the size of a
cube of by by or 10
18 m
3, and not (10
6 m
3)
Computing
In some fields of
computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...
, ''mega'' may sometimes denote 1,048,576 (2
20) of information units, for example, a megabyte, a megaword, but denotes (10
6) units of other quantities, for example, transfer rates: = . The prefix ''
mebi-'' has been suggested as a prefix for 2
20 to avoid ambiguity.
See also
*
Binary prefix
A binary prefix is a unit prefix for multiples of units. It is most often used in data processing, data transmission, and digital information, principally in association with the bit and the byte, to indicate multiplication by a power of& ...
*
Mebibyte
*
Order of magnitude
An order of magnitude is an approximation of the logarithm of a value relative to some contextually understood reference value, usually 10, interpreted as the base of the logarithm and the representative of values of magnitude one. Logarithmic di ...
*
RKM code
The RKM code, also referred to as "letter and numeral code for resistance and capacitance values and tolerances", "letter and digit code for resistance and capacitance values and tolerances", or informally as "R notation" is a notation to speci ...
References
External links
{{wiktionary, mega-
BIPM website
SI prefixes
he:תחיליות במערכת היחידות הבינלאומית#מגה